1) Field of the Invention
The present invention relates to a system for manufacturing a bonded sheet material.
2) Description of the Related Art
A system for manufacturing a bonded sheet material (corrugated fiberboard material) is made up of a single facer for forming a single faced bonded sheet material by sticking a back linerboard and a wave-shaped corrugated medium together, and a double facer for forming a double faced bonded sheet material by sticking the single faced bonded sheet material and a front linerboard together.
Each of the back linerboard, the corrugated medium, the single faced bonded sheet material and the front linerboard is preheated by a heating means before the bonding in order to adjust moisture (water) content.
So far, the heating quantity of the aforesaid preheating has been set by the perception and experience of an operator on the basis of a feed speed, kind and others of an object to be heated. However, the setting of the heating quantity based on the perception and the experience is unreliable; therefore, difficulty is encountered in stably manufacturing a bonded sheet material with less bonding failure and less warp at all times.
The present invention has been developed in consideration of such a problem, and it is therefore an object of the present invention to provide a bonded sheet material manufacturing system capable of setting optimum moisture content of sheet members to be bonded to each other to stably manufacture a bonded sheet material with less bonding failure and less warp at all times.
For this purpose, in accordance with the present invention, there is provided a system for manufacturing a bonded sheet material by sticking various types of sheet members together after separately heating the sheet members through the use of individual sheet member heating means, the system comprising moisture content detecting means provided for at least one of the sheet members for detecting moisture content of the sheet member or a parameter correlating with the moisture content, and control means for controlling the sheet member heating means on the basis of detection information from the moisture content detecting means so that the moisture content approaches a predetermined optimum moisture content.
In this case, preferably, the sheet member is any one of a back linerboard, a corrugated medium and a single faced bonded sheet material.
In addition, preferably, the sheet member heating means includes a heating roll for heating the sheet member in a state where the sheet member is wound around its circumferential surface and winding angle adjusting means for adjusting a winding angle of the sheet member with respect to the heating roll, and the control means controls the winding angle adjusting means. In this case, it is also appropriate that the winding angle adjusting means includes a guide roll for bringing the sheet member into contact with the heating roll and guide roll moving means for moving the guide roll on the circumferential surface of the heating roll.
Still additionally, preferably, the sheet member heating means includes a heating roll for heating the sheet member in a state where the sheet member is wound around its circumferential surface and valve means for adjusting a quantity of supply of heating steam to the interior of the heating roll, and the control means controls the valve means.
Moreover, preferably, the control means comprises a first control element for feedback-controlling the sheet member heating means when a deviation between desired moisture content and the moisture content detected by the moisture content detecting means is equal to or below a predetermined value and a second control element for feedforward-controlling the sheet member heating means when the deviation therebetween is more than the predetermined value.
Still moreover, the control means further includes a third control element for controlling the sheet member heating means to heat the sheet member to a preset temperature agreeing with an order change during the order change.
Yet moreover, the control means further includes a fourth control element for, when a feed speed of the sheet member is lower than a predetermined speed, controlling the sheet member heating means to heat the sheet member to a preset temperature agreeing with the lower feed speed than the predetermined speed.
In addition, preferably, a plurality of heating means each equivalent to the sheet member heating means are provided, and when a total heating quantity of the plurality of heating means reaches an excessive value, the control means decreases the heating quantities of the plurality of heating means successively starting from the upstream side heating means.
Still additionally, preferably, a plurality of heating means each equivalent to the sheet member heating means are provided, and when a total heating quantity of the plurality of heating means does not reach a required value, the control means increases the heating quantity of the plurality of heating means successively starting from the downstream side heating means.
Yet additionally, it is also appropriate that a temperature sensor is used as the moisture content detecting means, or that a moisture sensor is used as the moisture content detecting means.
Furthermore, it is also appropriate that the bonded sheet material manufacturing system further comprises scanning means for shifting the moisture content detecting means to scan the sheet member in a width direction of the sheet member and time-averaging means for time-averaging the outputs of the moisture content detecting means scanning-shifted by scanning means.
Still furthermore, it is also appropriate that a plurality of moisture content detecting means each equivalent to the aforesaid moisture content detecting means are located at a predetermined interval in a width direction of the sheet member, and width direction averaging means is further provided to average the outputs of the plurality of moisture content detecting means.
According to this bonded sheet material manufacturing system, the sheet members to be bonded heated by a heating means to optimize their moisture content, thus stably manufacturing a high-quality bonded sheet material with less bonding failure and less warp at all times.
In addition, the optimum moisture content based on a feed speed, a type of sheet member, a basic weight and others can be optimized through the heating by the heating means, which contributes to improvement of operability and manpower-saving.